Toilet facilities in locations visited by a large number of people, such as those in motorway service stations, have become a location for advertising. Sanitary appliances provided with one or more sensors may be used for identifying when such advertising should start and when it can be terminated.
One such sanitary appliance is known from BE-1016416A6. This prior art document proposes the use of a capacitive sensor and an electronic circuit for reading the capacitive sensor. The reading circuit transmits a signal to a processor to which also a display is coupled. The display can be used for games, for information on the urine flow and the provision of messages and advertisement.
The capacitive sensor is located on a rear side of the receptacle. Flow of urine in the receptacle at a location approximately opposite to the capacitive sensor may be detected as a change in capacitance.
It has turned out that the capacitive sensor does not meet the requirements. Constituent portions of the urine typically adhere to the flow surface of the receptacle, at least in some areas. This clearly depends on the frequency and the flow of a cleaning liquid, which typically is water. As a result thereof, the capacitance of the appliance in a non-use period (the background capacitance) increases. This complicates a distinction between flow of urine before the sensor (in the typically short period that this occurs) and the background capacitance. It has to be understood, in relation thereto, that the capacitance anyhow includes a component representative of the receptacle itself. The receptacle typically is a body of ceramic, dielectric material. The urine flow thus constitutes only an addition to the background capacitance.